Current Research

Our research focuses on understanding the behavior of advanced composite materials for the advancement and benefit of society. These lightweight materials have helped reduce fuel consumption in airplanes, automobiles, and buses. They have also been used in renewable energy sources such as wind blades and fuel cells.  We study them at the nano, micro, and macro-level as they are formed into useful products and address the pertinent physics and incorporate it into numerical simulations for process and product design for composite materials.  This involves focusing on material characterization, development of constitutive models over multi-scales present in the material, describing the relevant transport phenomena, formulation of process models and familiarity with efficient numerical methods to create computer simulations.

Sandwich structures, consisting of two (frequently composite) facesheets bonded on either side of a low-density core material. These materials display excellent out-of-plane compression and shear properties with very low areal density. One of the processes to manufacture sandwich structures are called co-cure. In this process, sandwich structures are co-cured to bond partially cured thermoset prepreg facesheets with an adhesive layer to either sides of the honeycomb core under a pre-defined pressure and temperature cycle in an autoclave. The co-cure of honeycomb core sandwich structures is strongly dependent on the materials and process parameters, and physical phenomena, occurring simultaneously, such as consolidation of prepreg facesheets, bond-line formation, porosity development within bond-line and core pressure evolution. This research describes the fundamental physics associated with the co-cure process of honeycomb core sandwich structures. [Navid Niknafs, Pavel Simacek, Suresh Advani]

The research include developing and understanding of the physical and mechanical characteristics of the incoming tape material and how the handling and machinery components affect these parameters. A key component in optimizing the tape placement of thin ply material is the development of a comprehensive model of the process that captures the controllable machine parameters in the thin-ply tape placement. The modeling will initially include the characterization of the thin ply microstructure and other critical parameters necessary to formulate a tape tension/compression. This will be used to provide guidance for machine modifications to existing or new processing equipment. In addition, test panels will be fabricated using the modified process conditions to demonstrate the improvements in mechanical properties compared to prior test panel results. [Verena Gargitter, Uday Kiran Balaga, Suresh Advani]

This project focuses on the finite element implementation of a physics-based model describing the behavior of uncured prepreg during autoclave processing. The goal is to develop a tool that can predict the final porosity distribution in parts with complex curvatures (i.e. corners) given a set of material and process parameters. Corner areas in composites are often sources of defects in final parts, giving higher than acceptable porosity. Multiple factors at each stage of the manufacturing process contribute to the qualities of the final part, and they can lead to significant variability of those qualities. Some example factors that influence the final properties include the part geometry, layup procedures, prepreg fiber and resin type, and autoclave conditions. The objectives of this project are to model the behavior of the prepreg material, identify which factors have the greatest effect on final part properties, characterize the necessary parameters, and utilize the finite element simulation results to optimize final part properties.[Pavel Simacek, Christopher Blackwell, Suresh Advani]

In co-curing of sandwich structures, the resin saturing the fiber plies of the facesheet are in an uncured liquid state. During processing, vacuum pressure is applied to the part which is enveloped in a vacuum bag. It is demonstrated that gas from the core volume can permeate through the facesheets only by way of desaturation of the liquid resin phase. The degree of desaturation in turn dictates the permeability to the gas phase. The gas pressure decay over time in the core volume is predicted my numerically solving for the transport of the liquid phase in conjunctiong with the gas phase. [Thomas A. Cender, Navid Niknafs, Suresh Advani]

This project focuses on structural batteries. One key area is the adhesive bonding between multiple layers of cathode, anode, separator, and electrodes. Wet electrolytes are the most used due to high specific energy and longevity, but they don’t allow strong mechanical bonding between constituent layers. Investigation into bonding between battery layers within a wet electrolyte environment is being done.  An empirical adhesive strength model specifically when in the presence of electrolyte is developed. [Wesley Connor, Suresh Advani (co-advisor), Ajay Prasad (advisor)]

Nafion membranes are used in fuel cells to separate the anodic and cathodic compartments which makes chemical energy transformation to electrical energy possible. It is the standard of choice for its excellent proton conductivity, chemical resistivity and high mechanical strength in the strongly acidic environments of H2-O2 fuel cells. However, in the presence of acidic environment and Pt catalysts, Nafion has a tendency of forming peroxide and hydroxide radicals. These radical unzip the membrane, reducing its length and therefore compromising the properties over its lifetime of operation. I am working on modifying the polymer backbone to incorporate functionalities which prevent this degradation. [Tanya Agarwal, Suresh Advani (co-advisor), Ajay Prasad (advisor)]

Sonijector LLC's ( patented variable area ejector which replaces the power-hungry, corrosion prone conventional pumps used to recirculate hydrogen in fuel cell systems.  It has virtually no moving parts and consumes only a few watts of power. Currently this part is made from anodized aluminum. In this project the objective is to redesign the ejector to manufacture it with short fiber composites using the injection molding process. The design and analysis ensured that the composite part can structurally withstand internal hydrogen pressures with nominal wall thickness of 3mm-5mm. Testing of the injection molded part will be carried out to ensure functionality and structural integrity of the modified ejector. [Sophie Sharafi, Paul Dason Samuel, Suresh Advani]

Traditional power management system of fuel cell/battery vehicles focus mainly on the fuel efficiency and rarely on the degradation. The current project studies the effect of adding the degradation of fuel cell/battery into power management. A detailed degradation model of the fuel cell was built to predict the loss of performance over time. It has been shown that including degradation can dramatically affect the power demands on fuel cell stack which resulted in major improvement on its lifetime. A follow-up sizing study has also been conducted to provide guidance on the optimal sizing between fuel cell and battery when degradation is considered. The latest testing bus has also been fitted with an on-board computer to collect driving data as well as receiving real-time data, the goal is to study the effectiveness of connected vehicle technologies on power management. [Yongqiang Wang, Suresh Advani (co-advisor), Ajay Prasad (advisor) ]